1,086 research outputs found
Earth Occultation Imaging of the Low Energy Gamma-Ray Sky with GBM
The Earth Occultation Technique (EOT) has been applied to Fermi's Gamma-ray
Burst Monitor (GBM) to perform all-sky monitoring for a predetermined catalog
of hard X-ray/soft gamma-ray sources. In order to search for sources not in the
catalog, thus completing the catalog and reducing a source of systematic error
in EOT, an imaging method has been developed -- Imaging with a Differential
filter using the Earth Occultation Method (IDEOM). IDEOM is a tomographic
imaging method that takes advantage of the orbital precession of the Fermi
satellite. Using IDEOM, all-sky reconstructions have been generated for ~sim 4
years of GBM data in the 12-50 keV, 50-100 keV and 100-300 keV energy bands in
search of sources otherwise unmodeled by the GBM occultation analysis. IDEOM
analysis resulted in the detection of 57 sources in the 12-50 keV energy band,
23 sources in the 50-100 keV energy band, and 7 sources in the 100-300 keV
energy band. Seventeen sources were not present in the original GBM-EOT catalog
and have now been added. We also present the first joined averaged spectra for
four persistent sources detected by GBM using EOT and by the Large Area
Telescope (LAT) on Fermi: NGC 1275, 3C 273, Cen A, and the Crab
Simulación por elementos finitos de la articulación temporomandibular
En los últimos años, las patologías asociadas a la articulación temporomandibular (ATM) han
cobrado una gran importancia en odontología y patología. Las disfunciones de esta articulación
están relacionadas con la inestabilidad mecánica y el movimiento irregular de los componentes
biomecánicos que la componen. Dentro de los diferentes elementos que forman esta articulación, es
el disco articular la pieza clave dentro de la misma, ya que absorbe las tensiones durante el
funcionamiento de la mandíbula, proporciona un adecuado contacto entre las superficies óseas y
proporciona estabilidad a la articulación. En este trabajo se desarrollaron dos modelos de elemento
finitos bidimensionales de la ATM, uno para una articulación sana y otro para una patológica
afectada de un desplazamiento anterior del disco. En ambos modelos de elementos finitos se introdujeron
diferentes modelos de comportamiento para simular de manera real el comportamiento del
disco articular. Las simulaciones realizadas resultaron ser fieles al comportamiento biomecánico
de la ATM real tanto sana como patológica, obteniéndose resultados cualitativos contrastados con
la experiencia clínica. Por otro lado, se demostró la necesidad de introducir modelos de comportamiento
complejos para simular de manera real el funcionamiento de esta articulación.Peer Reviewe
A feature-rich transmission spectrum for WASP-127b
WASP-127b is one of the lowest density planets discovered to date. With a
sub-Saturn mass () and super-Jupiter radius
(), it orbits a bright G5 star, which is about to
leave the main-sequence. We aim to explore WASP-127b's atmosphere in order to
retrieve its main atmospheric components, and to find hints for its intriguing
inflation and evolutionary history. We used the ALFOSC spectrograph at the NOT
telescope to observe a low resolution (, seeing limited) long-slit
spectroscopic time series during a planetary transit, and present here the
first transmission spectrum for WASP-127b. We find the presence of a strong
Rayleigh slope at blue wavelengths and a hint of Na absorption, although the
quality of the data does not allow us to claim a detection. At redder
wavelengths the absorption features of TiO and VO are the best explanation to
fit the data. Although higher signal-to-noise ratio observations are needed to
conclusively confirm the absorption features, WASP-127b seems to posses a
cloud-free atmosphere and is one of the best targets to perform further
characterization studies in the near future.Comment: Accepted for Publication A&A Letters, May 22nd, 201
Caracterización y cartografía fitoclimáticas del bosque nativo subantártico en la Isla Grande de Tierra del Fuego (Patagonia, Argentina)
Isla Grande de Tierra del Fuego is especially peculiar in phytoclimatic terms, situated as it is at an extreme southerly latitude, surrounded by large water masses and close to the great mass of Antarctic ice. Its main peculiarities in this sense are the coolness of its summers and a very narrow temperature range. As a result, the woodland landscapes in the parts with forest cover are dominated by microphyllous broadleaf physiognomies, both evergreen and deciduous, of the Nothofagus genus. This paper reports a more in-depth investigation of the hitherto little-known phytoclimatic conditions in that territory which included calibration and validation of a model of phytoclimatic suitability that addresses the principal plant physiognomic units and phytoclimatic mapping. It discusses the causes behind the presence of broadleaf formations in thermal conditions which in the northern hemisphere would allow only coniferous formations or no tree formations at all, and also the edaphic peculiarities that may explain the presence of a evergreen species like Nothofagus betuloides in subantarctic mixed forests.La Isla Grande de Tierra del Fuego presenta una muy marcada originalidad fitoclimática por su posición en latitudes muy australes, estar rodeada por grandes masas de agua y por su cercanía a la gran masa de hielo polar antártica. Esta originalidad se traduce en un escaso calor estival y una oscilación térmica muy reducida como principales peculiaridades, dando lugar en sus porciones arboladas a paisajes boscosos dominados por fisionomías planifolias de carácter micrófilo, tanto perennifolias como caducifolias del género Nothofagus. Este trabajo profundiza en las hasta hoy escasamente conocidas condiciones fitoclimáticas de este territorio, mediante la calibración y validación de un modelo de idoneidad fitoclimática respecto de las principales unidades fisionómicas de vegetación y el establecimiento de una cartografía fitoclimática. Se discuten las causas que provocan la existencia de formaciones planifolias en condiciones térmicas que darían lugar a formaciones aciculifolias o desarboladas en el hemisferio Norte, así como las particularidades edáficas que condicionan la presencia de la estrategia perennifolia representada por Nothofagus betuloides en los bosques mixtos subantárticos
Beyond the First Recurrence in Scar Phenomena
The scarring effect of short unstable periodic orbits up to times of the
order of the first recurrence is well understood. Much less is known, however,
about what happens past this short-time limit. By considering the evolution of
a dynamically averaged wave packet, we show that the dynamics for longer times
is controlled by only a few related short periodic orbits and their interplay.Comment: 4 pages, 4 Postscript figures, submitted to Phys. Rev. Let
Reconstructing complex lineage trees from scRNA-seq data using MERLoT
Advances in single-cell transcriptomics techniques are revolutionizing studies of cellular differentiation and heterogeneity. It has become possible to track the trajectory of thousands of genes across the cellular lineage trees that represent the temporal emergence of cell types during dynamic processes. However, reconstruction of cellular lineage trees with more than a few cell fates has proved challenging. We present MERLoT (https://github.com/soedinglab/merlot), a flexible and user-friendly tool to reconstruct complex lineage trees from single-cell transcriptomics data. It can impute temporal gene expression profiles along the reconstructed tree. We show MERLoT’s capabilities on various real cases and hundreds of simulated datasets
Quantum-well states in ultrathin Ag(111) films deposited onto H-passivated Si(111)-(1x1) surfaces
Ag(111) films were deposited at room temperature onto H-passivated
Si(111)-(1x1) substrates, and subsequently annealed at 300 C. An abrupt
non-reactive Ag/Si interface is formed, and very uniform non-strained Ag(111)
films of 6-12 monolayers have been grown. Angle resolved photoemission
spectroscopy has been used to study the valence band electronic properties of
these films. Well-defined Ag sp quantum-well states (QWS) have been observed at
discrete energies between 0.5-2eV below the Fermi level, and their dispersions
have been measured along the GammaK, GammaMM'and GammaL symmetry directions.
QWS show a parabolic bidimensional dispersion, with in-plane effective mass of
0.38-0.50mo, along the GammaK and GammaMM' directions, whereas no dispersion
has been found along the GammaL direction, indicating the low-dimensional
electronic character of these states. The binding energy dependence of the QWS
as a function of Ag film thickness has been analyzed in the framework of the
phase accumulation model. According to this model, a reflectivity of 70% has
been estimated for the Ag-sp states at the Ag/H/Si(111)-(1x1) interface.Comment: 6 pages, 6 figures, submitted to Phys. Rev.
Comorbidity and osteoporotic fracture: approach through predictive modeling techniques using the OSTEOMED registry
Purpose To examine the response to anti-osteoporotic treatment, considered as incident fragility fractures after a minimum
follow-up of 1 year, according to sex, age, and number of comorbidities of the patients.
Methods For this retrospective observational study, data from baseline and follow-up visits on the number of comorbidities,
prescribed anti-osteoporotic treatment and vertebral, humerus or hip fractures in 993 patients from the OSTEOMED registry
were analyzed using logistic regression and an artificial network model.
Results Logistic regression showed that the probability of reducing fractures for each anti-osteoporotic treatment consid-
ered was independent of sex, age, and the number of comorbidities, increasing significantly only in males taking vitamin
D (OR = 7.918), patients without comorbidities taking vitamin D (OR = 4.197) and patients with ≥ 3 comorbidities taking
calcium (OR = 9.412). Logistic regression correctly classified 96% of patients (Hosmer–Lemeshow = 0.492) compared with
the artificial neural network model, which correctly classified 95% of patients (AUC = 0.6).
Conclusion In general, sex, age and the number of comorbidities did not influence the likelihood that a given anti-osteoporotic
treatment improved the risk of incident fragility fractures after 1 year, but this appeared to increase when patients had been
treated with risedronate, strontium or teriparatide. The two models used classified patients similarly, but predicted differently
in terms of the probability of improvement, with logistic regression being the better fit
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